on the Influence of the Brain, &c. 383 
the atmospheric air ; first, because the quantity is so small that 
the omission can occasion no material error ; and secondly, 
because the object is to ascertain, not so much the absolute, 
as the relative quantities of carbonic acid evolved by animals 
breathing under different circumstances. 
The experiments which I shall first notice, were made on 
the respiration of animals in a natural state. 
Experiment 1. Thermometer barometer not noted. 
A young rabbit was allowed to remain under the bell-glass 
during 30 minutes. The respired air at the end of this time 
was found to contain 3V of carbonic acid. 
It was ascertained that the rabbit occupied the space of 50 
cubic inches. 
The capacity of the bell-glass = 502 cubic inches. 
That of the gum-bottle 52 cubic inches. 
The air in the tubes and bladder = 2 cubic inches. 
Then 5 °* + s* + *- 5 ° = 2* = S5 . 3 . 
The rabbit therefore in 30 minutes gave out 25.3 cubic inches 
of carbonic acid, and consumed the same quantity of oxygen 
gas, which is at the rate of 50.6 in an hour. 
Exp. 2. Thermometer 65°, barometer 30.1 inches. 
A somewhat smaller rabbit was allowed to remain under 
the bell-glass during 30 minutes. The respired air contained 
~ ¥ of carbonic acid. The animal occupied the space of 48 
cubic inches. 
502 + 52 + 2 — 48 508 
i 8 ' TF 
= 28.22. 
The carbonic acid evolved was therefore equal to 28.22 cubic 
inches in half an hour, which is at the rate of 56. 44 cubic inches 
in an hour. 
